Prostaglandins and thromboxanes are potent vasoactive compounds that may play a role in regulating organ blood flow. We have previously demonstrated that prostaglandins are critical factors in maintaining renal blood flow in patients with chronic liver disease. The current study is designed to determine if changes in renal prostaglandins or thromboxane production play a role in the terminal renal failure that accompanies severe liver disease (hepatorenal syndrome). For this study animal models of liver disease are used. In addition urinary excretion of the prostaglandins are measured by radioimmunoassay and bioassay in patients with severe liver disease.